The Evolution of Genetic Code in Genetic Programming

In most Genetic Programming (GP) approaches, the space of genotypes, that is the search space, is identical to the space of phenotypes, that is the solution space. Developmental approaches, like Developmental Genetic Programming (DGP), distinguish between genotypes and phenotypes and use a genotypephenotype mapping prior to fitness evaluation of a phenotype. To perform this mapping, DGP uses a problem-specific manually designed genetic code, that is a mapping from genotype components to phenotype components. The employed genetic code is critical for the performance of the underlying search process. Here, the evolution of genetic code is introduced as a novel approach for enhancing the search process. It is hypothesized that code evolution improves the performance of developmental approaches by enabling them to beneficially adapt the fitness landscape during search. As the first step of investigation, this article empirically shows the operativeness of code evol..